The production of carboxylic acid esters via homologation has already been described in the literature. It is known from European Patent Application No. 31606 that the stoichiometry of the known reactions of methyl acetate with carbon monoxide and hydrogen can be altered most advantageously to produce one mole of ethyl acetate and two moles of acetic acid from two moles of methyl acetate. The catalytic system comprises three metal compounds: a ruthenium compound, a further Group VIII metal compound, and a bromide or iodide of a Group II or transition metal, preferably in the presence of a promoter, typically an amine or a phosphine.
It has been described and claimed in our co-pending application Ser. No. 395,946, filed July 7, 1982 (K-0478), now abandoned, that an alkyl or acyl iodide or bromide can replace the Group II or transition metal iodide or bromide in the catalytic system as disclosed in European Patent Application No. 31606, provided that the quantity of amine in the reaction mixture does not exceed a certain rather low level.